This invention relates generally to feeding string, more particularly to a method of and apparatus for precision feeding of string forward to apparatus in which string is utilized.
The invention is especially concerned with feeding string forward from a supply to apparatus in which predetermined lengths of string are utilized, such as a high speed stringer for attaching string to items.
The term xe2x80x9cstringxe2x80x9d as used herein encompasses what is ordinarily regarded as xe2x80x9cstringxe2x80x9d as well as flexible string-like strands.
In general, the method of the invention feeds string forward from a supply. The method comprises entraining the string coming from the supply around at least one feed roll, driving the roll in the direction for feeding the string forward, subjecting the string to a force in the reverse direction upstream from the roll, and subjecting the string to a forwarding force downstream from the roll.
Apparatus of the invention generally involves a feed roll, a motor for driving the feed roll in the direction for feeding the string forward, a retarder for subjecting the string to force in the reverse direction upstream from the roll for retarding its forward feed, and an accelerator for subjecting the string to a forwarding force downstream from the roll for exerting a pull on the string to tension the portion of the string between the retarder and the accelerator. A feature of the invention is the driving of the feed roll continuously in cycles each involving varying speed of the roll for feeding predetermined lengths of string forward per cycles. A further feature is the carrying out of the variable speed drive by different means.
Other features will be in part apparent and in part pointed out hereinafter.